Me and my bf have being fairly conservative in the bedroom but I'm getting increasingly bored and if I am he must be, I want to try some more things but not sure how to see where he stands, I'm more a sub and wish he could be more I guess aggressive and dominating but I don't want him to change what he wants
Help?

There have been many threads about a similar situation here, so you might want to browse back a few pages and check the BDSM Library (there's a sticky on top of this forum for it), too.

Then again, I think just asking for a spanking or for him to take you rougher or something like that during sex is a pretty easy and innocent enough way to see if he's into it. Later talk about how great it was and how you've been thinking about it for a long time and what more you'd like to experience etc.

If he's clearly not into it when you ask for a spanking, you can always say afterwards that you got carried away with your words and requests because the sex was so awesomely hot. And even if your suggestion doesn't amount to anything when you're asking, at least you've said something and it'll probably be easier to get back to the subject later on.

__________________WANDERING CLOUDS HAVE FASTENED THEMSELVES TO THE MOUNTAIN'S EDGE,
FOR ENDLESS HOURS THEY STAND IN SILENCE AND WAIT-Edith Södergran: Wandering clouds

Spanking is an easy first step and can vary from a few "love taps" to a good ass reddening. Aggressive dirty talking is also possible using "demands" to do things....."get on your fucking knees and suck my cock, now!", "spread your fucking legs and open your cunt for me." If he's embarrassed, or if you're embarrassed with aggressive demands then sometimes silence and surprise can also be stimulating. That is, like you wearing a blindfold and being bound and not knowing what he'll do next.

As others have said, communication is important. There are some books and articles that you can both read if you are BOTH into trying these sorts of things. If one wants it and the other is very uncomfortable with it, it won't bring you closer, it could split you up. Be careful and take baby steps. Men, like me, were raised to be very gentle with women and to not be aggressive. It took me some time and experience to know how to let that side of me out to play, when women wanted more aggression, and to respect both those who liked it and those who didn't. We are all different.